For example DE 10 2008 010 609 A1 discloses a chisel-chisel holder arrangement in which a chisel is supported in a chisel holder, wherein the chisel holder in turn is insertable in a base holder. While the base holder can be considered as a tool holder in the sense of the device recited supra the chisel holder can be interpreted as support element according to the device described supra. The chisel which engages the material to be machined during machining operations can be furthermore interpreted as a cutting tool in the sense of the device recited supra.
In the device recited in the publication document the chisel is, as common in the art, inserted into a bore hole of the chisel holder and attached at this location for example through a clamping sleeve. The basic principle of arranging a cutting tool (in the recited document the chisel) at an associated milling device and configuring the cutting tool as a so called round shaft chisel rotating about its longitudinal axis has been a technical standard for quite a while and is being used in many applications. Due to the particularly strong force impact during milling operations all components of the device described supra are subject to substantial wear. This applies in particular for the cutting tool, wherein in particular the portion of the cutting tool is affected the most which is brought into direct engagement with the material to be machined (for example a chisel). Based on the high mechanical loadings the associated relatively short service lives of the cutting tools are accepted.
Various developments therefore relate in particular to the problem of low service life of portions of the device that do not come in contact with the material to be machined. Many innovations were already able to provide improvements. Current devices, however, do not sufficiently address the problem of high wear of the support element which is only used for supporting or receiving the cutting tool. Classic wear effects can be created for example in that high transversal forces transmitted from the cutting tool to the support element lead to a deformation of the initial cylindrical receiver of the support element so that the receiver in particular in a upper section loses its essentially circular cross section which becomes increasingly ellipsoid. This impacts the support of the cutting tool included therein significantly and prevents for example a reliable rotation of the cutting tool (for example provided in the form of a round shaft chisel) about its longitudinal axis. Furthermore, the cutting performance of the cutting tool is reduced since the orientation of the cutting tool with an optimum chip angle between the associated cutting element and the material to be processed is lost. Also the large pulsating axial forces transmitted through the chisel head into the support element in conjunction with the chisel rotation and abrasive components of the machine material (“grinding particles”) lead to wear of the tool holder in the sense of a material removal in axial direction which in turn reduces the stability of the support. Due to this wear of the support element relatively frequent replacement of the support element is necessary. This is undesirable for several reasons.
On the one hand side the support element is typically a relatively massive and large component (c.f. tool holder according to DE 10 2008 010 609 A1), which respectively cause considerable material costs. On the other hand side replacing a bearing element of this type is rather complex in the prior art since the bearing element is typically welded together with an associated tool holder, for example a base holder and has to be disengaged with a cutting torch and subsequently welded on again so that besides high material costs high wages and down times are incurred when replacing the support element.
The utility model DE 296 23 215 U1 addresses the problem of the support element wearing out (chisel holder c.f. DE 296 23 215 U1) by using a support element. The support element is placed in a portion between the cutting tool and the bore hole of the support element so that impact loads which originate from milling operations are not directly passed from the cutting tool to the support element but are captured by the support element. However, it is detrimental that the illustrated support element is either sunk with a conical plug insert in an also conical dead hole and wedged therein or attached at the support element through a solder joint or a welded joint. Both attachment variants have the effect that the support element can either not be removed at all or that it can only be removed with substantial complexity, for example when the support element itself is heavily worn and cannot perform its protective function relative to the change holder anymore.